Manifold Absolute Pressure Sensor
2021 Honda Civic · 1.5L I4 Turbo
Sensor Type
piezoresistive
Waveform Type
dc-variable
Location
Mounted on intake manifold plenum, rear of engine near firewall
Pins
3-pin connector
Timebase
100ms/div
Voltage Scale
1V/div
Trigger
2.5V, center screen
Wiring
Green/White (5V reference), Green/Black (signal output), Black/White (sensor ground)
Expected Voltage Range
At Idle
0.8V to 1.4V
At Higher RPM
3.8V to 4.7V
Expected Pattern
Smooth analog voltage with slight pulsations matching engine firing at idle, sharp increase under boost
Known-Good Waveform
At idle with engine warmed up, MAP should read 0.8-1.4V indicating intake vacuum of 16-20 inHg. Key-on-engine-off should read approximately 4.5V (atmospheric pressure at sea level). Under wide-open throttle with turbo boost, voltage rises to 3.8-4.7V representing 15-20 psi boost pressure. Signal should show rhythmic pulsations at idle frequency corresponding to intake valve events, indicating good sensor response time.
Common Failure Patterns
Voltage reads near atmospheric (4.5V) at idle or doesn't drop below 3.0V
Cause: Vacuum hose disconnected, cracked intake manifold, or failed sensor diaphragm
Diagnostic Tips
The L15B7 turbo engine relies heavily on MAP for boost control and fuel calculation; compare MAP voltage to boost gauge reading under load. Common issue is the small vacuum line to sensor cracking at the manifold connection point causing false lean codes and poor turbo response.
Related Diagnostic Trouble Codes
P0105P0106P0107P0108P0109
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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